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21 Cards in this Set
- Front
- Back
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In Michaelis-Menton kinetics, what is [S], V, Km, and Vmax? |
[s] = concentration of the substrate V = velocity Km= Substrate concentration. concentration of the substrate that gets the reaction to half of Vmax. Vmax= Directly proportional to the enzyme concentration (the enzyme available) |
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Enzymatic reactions that exhibit a sigmoid curve usually indicates... |
cooperative kinetics |
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The higher the affinity for the enzyme... |
the faster it reaches Vmax. Therefor the lower Km will be.
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Competetive inhibitors affect _____ but not _____ |
Competetive inhibitors affect Km (by increasing it) but not Vmax |
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Non-competetive inhibitors affect ____but not____ |
Non-competetive inhibitors affect Vmax(by lowering it) but not Km. |
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What is the definition of volume of distrubution? |
theoretical volume that the absorbed drug occupied in the plasma. |
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What characteristics do drug molecules need to have in order to reach a high Vd? |
Small hydrophilic (ECF) or lipophilic (all tissues, especially if bound to tissue protein) |
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What is the clearance formula? |
CL= rate of elimination of drug/plasma concentration= Vd x Ke(elimination constant) |
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What is the definition of clearance? |
The volume of plasma cleared of drug per unit time. |
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What is the definition of Half Life? |
time required to eliminate 50% of the drug. |
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What does Efficacy mean? |
Maximal effect a drug can produce. Does not have to do with potency. |
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If drug A (20mg) and drug B(10mg) are given at the same time and at 4 hours they have both achieved the same effect, what does this mean? |
That drug B is more potent |
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If drug A (20mg) and drug B(20mg) are given at the same time and at 4 hours drug A caused more effect than drug B, you can infer that.... |
Drug A is more efficacious |
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What type of drugs have high efficacy? |
antibiotics, antihistamines, decongestants |
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What types of drugs have high potency? |
chemotherapeutic, antihypertensive, lipid lowering drugs |
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How does a competitive antagonist affect the potency/efficacy? |
Shifts curve to the right (lowers potency bc you have to give more dose).
No change in efficacy. (bc the effect is the same)
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How does a noncompetitive antagonist/reversible competitive antagonist affect the potency/efficacy? |
Shifts curve down (lowers efficacy bc it does not reach maximum effect)
No change in potency (bc the dose is the same) |
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How does a partial agonist affect the potency/efficacy? |
Lower maximum effect, and the potency is an independent value.
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At higher therapeutic index.... |
The safer the drug is.
This happens if the lethal dose is high or the effective dose is low
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Some drugs with low therapeutic index are.. |
Seizure drugs Lithium Digoxin Warfarin
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the higher the therapeutic window ... |
You can give the medication frequently without risk o |
